Carbapenem-resistant Enterobacteriaceae (CRE) have spread rapidly around the world in the past few years, posing great challenges to human health. The plasmid-mediated horizontal transmission of carbapenem-resistance genes is the main cause of the surge in the prevalence of CRE. Therefore, the timely and accurate detection of CRE, especially carbapenemase-producing Enterobacteriaceae, is very important for the clinical prevention and treatment of these infections. A variety of methods for the rapid detection of CRE phenotypes and genotypes have been developed for use in clinical microbiology laboratories. To overcome the lack of efficient antibiotics, CRE infections are often treated with combination therapies. Moreover, novel drugs and emerging strategies appeared successively and in various stages of development. In this article, we summarized the global distribution of various carbapenemases. And we focused on summarizing and comparing the advantages and limitations of the detection methods and the therapeutic strategies of CRE primarily.

Combating plasmid-mediated carbapenem resistance is essential to control and prevent the dissemination of carbapenem-resistant Enterobacteriaceae (CRE). Here we conducted a proof-of-concept study to demonstrate CRISPR/Cas9-mediated resistance gene and plasmid curing can effectively re-sensitize CRE to carbapenems. A novel CRISPR/Cas9-mediated plasmid-curing system (pCasCure) was developed and electrotransferred into various clinical CRE isolates. The results showed that pCasCure can effectively cure blaKPC, blaNDM and blaOXA-48 in various Enterobacteriaceae species of Klebsiella pneumoniae, Escherichia coli, Enterobacter hormaechei, E. xiangfangensis and Serratia marcescens clinical isolates, with > 94% curing efficiency. In addition, we also demonstrated that pCasCure can efficiently eliminate several epidemic carbapenem-resistant plasmids, including the blaKPC-harboring IncFIIK-pKpQIL and IncN pKp58_N, blaOXA-48-harboring pOXA-48-like, blaNDM-harboring IncX3 plasmids, by targeting their replication and partitioning (parA in pKpQIL) genes. However, curing blaOXA-48 gene failed to eliminate its corresponding pOXA-48-like plasmid in a clinical K. pneumoniae isolate 49210, while further next generation sequencing revealed that it was due to IS1R mediated recombination outside the CRISPR/Cas9 cleavage site, resulting in blaOXA-48 truncation and therefor escaped plasmid curing. Nevertheless, the curing of carbapenemase genes or plasmids, including the truncation of blaOXA-48 in 49210, successfully restore their susceptibility to carbapenems, with > 8-fold reduction of minimum inhibitory concentration (MIC) values in all tested isolates. Taken together, our study confirmed the concept of using CRISPR/Cas9-mediated carbapenemase genes and plasmids curing to re-sensitize CRE to carbapenems. Further work is needed to integrate pCasCure in an optimal delivery system to make it applicable for clinical intervention.

Class 1 integrons were found to be widespread in P. aeruginosa isolated from clinical samples in the Zhenjiang area of China. The antibiotic resistance rates in class 1 integron-positive strains of P. aeruginosa were noticeably higher than those in class 1 integron-negative strains. PFGE showed that particular clones were circulating among patients.

The prevalence of carbapenem-resistant Enterobacteriaceae (CRE) is increasing globally, with different molecular mechanisms described. Here we studied the molecular mechanisms of carbapenem resistance, including clonal and plasmid dissemination, of 67 CRE isolates collected between 2012 and 2016 from a tertiary hospital in Eastern China, an CRE endemic region. Species identification and susceptibility testing were performed using the BD Phoenix Automated Microbiology System. Isolates were characterized by PCR (for carbapenemases, ESBLs, AmpC and porin genes), multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and conjugation transfer experiments. Selected blaKPC-2 -harboring plasmids were subjected to next-generation sequencing using the Illumina Miseq platform. Among the 67 CRE isolates, 42 Klebsiella pneumoniae, 10 Serratia marcescens, 6 Enterobacter cloacae, 2 Raoultella ornithinolytica, 2 K. oxytoca, 1 K. aerogenes, and 4 Escherichia coli isolates were identified. Six different carbapenemases were detected, including blaKPC-2 (n = 45), blaKPC-3 (n = 1), blaNDM-1 (n = 6), blaNDM-5 (n = 1), blaIMP-4 (n = 2), and blaVIM-1 (n = 2); blaOXA-48-like genes were not detected. One E. cloacae strain possessed both blaNDM-1 and blaKPC-3, while two E. cloacae isolates harbored blaNDM-1 and blaVIM-1. ESBLs (CTX-M, SHV, and TEM) and/or AmpC (CMY, DHA, and ACT/MIR) genes were also identified in 59 isolates, including 13 strains that lacked carbapenemases. Several insertions or stop codon mutations were found within porin genes of K. pneumoniae, E. coli and S. marcescens isolates, both with and without carbapenemases. The 42 K. pneumoniae isolates belonged to 12 different sequence types (ST), with ST11 being the most common, while the 6 E. cloacae isolates comprised 4 different STs. The 10 S. marcescens all shared the same PFGE pulsotype, suggestive of clonal spread. Complete plasmid sequencing and PCR screening revealed both intra-strain and inter-species spread of a common blaKPC-2-harboring plasmid in our hospital. Taken together, our study revealed extensive genetic diversity among CRE isolates form a single Chinese hospital. CRE isolates circulating in the hospital differ significantly in their species, STs, porin genes, carbapenemase genes, and their plasmid content, highlighting the complex dissemination of CRE in this endemic region.

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c Here, we report two Enterobacter cloacae sequence type 231 isolates coproducing KPC-3 and NDM-1 that have caused lethal infections in a tertiary hospital in China. The bla NDM-1 -harboring plasmids carry IncA/C 2 and IncR replicons, showing a mosaic plasmid structure, and the bla NDM-1 is harbored on a novel class I integron-like element. bla KPC-3 is located on a Tn3-⌬bla TEM-1 -bla KPC-3 -⌬Tn1722 element, flanked by two 9-bp direct-repeat sequences and harbored on an IncX6 plasmid. Carbapenemase-producing Enterobacteriaceae (CRE) strains have spread worldwide and have become a significant public health threat (1, 2). It is alarming that CRE isolates coproducing multiple carbapenemases recently emerged and pose significant challenges to our limited treatment strategies, as these bacteria tend to be extremely highly resistant (3-10). To date, the coexistence of Klebsiella pneumoniae carbapenemase 2 (KPC-2) and New Delhi metallo-␤-lactamase-1 (NDM-1) in single clinical isolates from different species, including K. pneumoniae, Enterobacter cloacae, Enterobacter hormaechei, and Citrobacter freundii, has been reported in Brazil, India, Pakistan,8,9). However, knowledge regarding the genetic content and plasmid structure of these multicarbapenemase-producing bacteria remains limited (3,6). In this study, we used next-generation sequencing to characterize the genomes of two KPC-3-and NDM-1-coproducing E. cloacae strains and their plasmids. Our analysis revealed distinct plasmid structures that, to our knowledge, have not been described previously.Two carbapenem-resistant E. cloacae strains (SZECL1 and SZECL2) were identified in a retrospective study on CRE at a tertiary-care hospital in China. They were isolated from sputum samples from two female patients (63 and 57 years old) admitted to the same intensive care unit in 2012. The two isolates were collected 11 days apart. The patients died 13 and 18 days after the isolation of the organisms as a result of severe pulmonary infections. Antimicrobial susceptibility testing showed that the two isolates, SZECL1 and SZECL2, had the same resistance profile (Table 1). They were resistant to all ␤-lactams and inhibitors, including imipenem, meropenem, ertapenem, and ceftazidime-avibactam, and were resistant to amikacin, gentamicin, tobramycin, ciprofloxacin, levofloxacin, moxifloxacin, and trimethoprim-sulfamethoxazole but remained susceptible to tetracycline, tigecycline, and colistin.Genotyping results showed that SZECL1 carries bla KPC-3 , bla NDM-1 , and bla , while SZECL2 harbors the same ␤-lactamase genes (bla , bla NDM-1 , and bla ) as SZECL1, with an additional bla CTX-M-15 gene (11,12). Multilocus sequence typing indicated that the two isolates were of the same sequence type, ST231 (13), and they displayed indistinguishable patterns in pulsed-field gel electrophoresis analysis, suggesting that these two isolates are closely related and may have evolved from the same ancestor.The bla KPC-3 -harboring plasmids in SZECL1 and SZECL2 were successfully transferred to...

Staphylococcus aureus is a common pathogen causing both hospital and community-acquired infections. Hemolysin is one of the important virulence factors for S. aureus and causes the typical β-hemolytic phenotype which is called complete hemolytic phenotype as well. Recently, S. aureus with an incomplete hemolytic phenotype (SIHP) was isolated from clinical samples. To study the microbiologic characteristics of SIHP, the special hemolytic phenotype of SIHP was verified on the sheep blood agar plates supplied by different manufacturers. Expression of hemolysin genes hla, hlb, hlgC, and hld of SIHP was detected by qRT-PCR and it was showed that expression of hlb in SIHP was obviously increased compared to the control S. aureus strains with complete hemolytic phenotype (SCHP), while the expression of hla, hlgC, and hld in SIHP was significantly decreased. In addition, the α-hemolysin encoded by gene hla was decreased obviously in SIHP compared to SCHP by western blot. All 60 SIHP strains were identified to be the methicillin resistant S. aureus (MRSA), and moreover these SIHP strains all contains mecA gene. The virulence gene tst were all present in SIHP, and the intracellular survival ability of SIHP was much greater than that of the gene tst negative S. aureus. We also found that IL-2, IL-6, and IL-17A secreted in the supernatant of SIHP infected macrophages increased significantly compared to tst negative control strains infected ones. MLST analysis showed that all of SIHP strains were classified into ST5 clone. To our knowledge, this study firstly showed that SIHP strains are a kind of methicillin resistant strains which express β-hemolysin highly and possess a potential high virulence, and it was suggested that SIHP should be paid more attention in hospital.

This paper evaluates the existing policy frameworks for mitigation of diffuse water pollution from agriculture (DWPA) in England and China. With reference to a conceptual model of the process of policy transfer or international lesson drawing, and possible constraints to this, it assesses whether and how China can draw lessons to improve current policy from the supra-national and national provisions of the EU and a member state that by 2016 had comprehensively implemented EU agricultural and environmental policy. DWPA is first analysed as a public policy challenge to inform specification of a generic framework for its mitigation. The current policy frameworks for mitigation of DWPA in England and China are evaluated, and their potential for improvement is assessed. A number of barriers to lesson drawing for regulation, incentive payments schemes and advice provision are diagnosed. These barriers are potentially least in relation to advice provision and its use to promote voluntary action by farmers. Given its structure and capabilities the public agricultural extension system in China is also recognised as a key resource. A focus on three policy approaches to mitigate DWPA in China is recommended: i) targeted regulation to a 'reference level' of large intensive livestock, and ultimately other large commercial farms; ii) strategic use of incentive payment schemes to protect water resources from DWPA; and iii) reorientation of the ethos and modalities of operation of the extension system, informed by international lesson drawing, with the aim of rebalancing farm productivity and environmental protection.